The invention refers to a single-blow shockwave generation device and its implementation process.
Shockwave generation devices are notably used in urological surgery for disintegration of urinary duct stones. The prior art includes two main types of shockwave generation devices: a first type concerning extra-corporeal shockwave generation devices, and a second type concerning percutaneous shockwave generation devices.
Disintegration devices of the first type use an electrical or piezo-electrical shockwave generator where the shockwave guide is comprised of a pocket containing a fluid, in contact with patient's body cooperating with an ellipsoidal reflector which receives a shockwave diffused into a wide space, to focus it through a widely open cone whose apex is located inside the urinary stone to be disintegrated, so that the shockwave is of low amplitude when it crosses through living tissues in order to reduce lesions to said tissues to the minimum possible extent, and of maximum amplitude when concentrated at cone apex.
Disintegration devices of the second type use, for example, specialized endoscopes to match the nature of the intervention to be performed, depending on the size and position of the urinary stone to be evacuated. When the stone is inside the kidney, the endoscope is introduced percutaneously directly into the kidney. When the stone is in the ureter, it is advisable to introduce the endoscope by natural paths via the bladder and up into the ureter. The shockwave is transmitted by a waveguide, which is a metallic rod of circular cross-section, of a diameter of ten to twenty tenths of a millimeter, and able to tolerate elastic deformation. The shockwave guide features a first end where the shockwave is generated and a second end which is applied against the stone.
Disintegration devices of the first type do not allow high amplitude shockwave production, due to risk of lesions to living tissues crossed through. Consequently, stone disintegration requires multiple shocks which reduce the stone into small fragments which can be evacuated through the urinary ducts.
Disintegration devices of the second type, notably that described in European patent EP0317507, use low amplitude shockwave trains whose characteristic feature is also to break the stone to be disintegrated into multiple fragments which can be eliminated by suction, washing, or evacuation through natural paths.
Disintegrated stone fragment elimination through natural paths is very painful, which makes elimination by washing preferable whenever possible, further to an intervention by endoscopy. These stone elimination modes feature a drawback, in that there always remains uneliminated stone debris which can act as a basis for new stone formation.
Gas sealing devices between moving parts in these devices generally include O-rings, for which sealing is obtained by cooperation, either between the higher and lower sealing circles of the O-rings pressed between two flat surfaces or through cooperation between an inner lateral sealing circle and an outer lateral sealing circle of the O-ring pressed between a revolution bore and a revolution cylinder. These sealing devices can be classified, for example, into three types of devices: a sealing device of the first type is comprised of an O-ring positioned in a groove machined in a bore and whose sealing is ensured by cooperation between the inner lateral sealing circle and the outer lateral sealing circle. A sealing device of the second type is comprised of an O-ring located in a groove machined in a revolution cylinder. A sealing device of the third type is comprised of an O-ring located in a circular groove undercut in a flat surface.